Heat induced failure of engine mounts is a problem experienced by vehicle manufactures for example due to certain vehicle designs which result in reduced air flow cooling of the engine compartment. Supplier of such mounts have been requested to submit concepts that primarily consist of using high temperature resistant polymers in the mount structure. However investigations have not revealed a substitute for the fatigue resistance of natural rubber.
As a solution, the invention disclosed herein combines materials within a mount design which utilizes the advantages of each material by separating the functions and contributions of the materials. A specially formulated natural rubber based material is used for the primary shock isolating (spring) element, while plastic is used as a non-conductible insulator, and a rubber cap or shroud is used for a convection and radiation heat path reducer
Savard U.S. Pat. No. 2,655,090 broadly discloses a thermal shroud for an engine mount, but does not show the relationship of the shroud to any mount structure. Law U.S. Pat. No. 5,1112,144 provides an elastomeric bearing structure which provides for thermal expansion and contraction. A central load member moves within rubber blocks and laminated with shaped metal plates which allow for thermal changes. These two patents reference problems with temperature, while Most of the remaining prior art is concerned with reducing wear and tear per se.
Wieme U.S. Pat. No. 4,278,726 discloses an energy absorbing element comprising a laminate of reinforced plastic bonded to vulcanized elastomer, namely a plastic core is laminated with two rubber layers.
Stimeling U.S. Pat. No. 4,744,539, Barrett U.S. Pat. No. 5,087,491, Fukahori et al U.S. Pat. No. 4,978,581 and Fukahori et al U.S. Pat. No. 4,830,927 disclose cushioning members having a laminated structure. In Stimeling, the laminate comprises elastomer layers bonded to metal layers. The Fukahori et al documents both show rigid metal layers bonded to viscoelastic flexible plates. Barrett broadly shows a laminate of stiff layers formed with viscoelastic layers.
The Fischer U.S. Pat. No. 4,887,788 discloses an energy absorbing pad comprising an elastomeric resilient element combined with elements of greater stiffness; column 4, lines 314.